My wife has a Ruger SR9c that she absolutely adores, but I'm slightly concerned about the Magazine Disconnect Safety. Could the MDS cause a light primer strike? In 500 rounds through my wife's gun, we've had exactly 2 failures to fire, both of which were light primer strikes, both with the 10 round magazine with the pinky extension in place, and both before we hit 300 rounds.

I know you can "fire" the striker with the magazine removed, but I'm assuming the MDS doesn't allow the striker to pass through the breech face. Would gripping the pistol very tightly with my monkey paws cause the pinky extension to "pull" the magazine down far enough that the MDS might engage? That's the only thing I can figure out that may have caused it. It happened once with her, and once with me. Both rounds fired fine when they were reloaded into the gun, so it wasn't bad ammo.

I'm VERY tempted to pull the MDS out, because those are the only 2 issues we've had with the gun (aside from the front sight being too far to the right, which I fixed with a dowel a while back), and it is about to become her carry gun.

It takes about 2 minutes to remove the magazine disconnect safety (MDS), and it is about as hard to put it back in if you ever want to resell the gun.

Look at http://www.ruger.com/resources/videos.html and select the SR9c dis-assembly video. It shows you how to take down the pistol and remove the striker. Once the striker is out, just lift out the MDS and re-assemble. (The MDS is that part he presses down with his index finger before removing the striker.)

Both the trigger and the mag release buttons will be lighter without the MDS.

I would probably remove the MDS, but I think it's unlikely that it's causing your light primer hits. The MDS doesn't interfere with the strikers movement through it's channel or the breach face. It works by keeping the trigger bar from contacting the sear, so when you pull the trigger it's not making contact with anything. As long as the trigger bar is contacting the sear, I doubt it would cause any other interference. I also don't see how removing the MDS would make any significant difference to the trigger weight.

I have a few more rounds through mine and the same number of FTF as you. Both with my wife shooting. I attributted it to a weak grip. Both occured after a good bit of shooting several other guns, and I figured her hands were tired. But based on what I understand anout the mag disconnect, I don't see how taking it out would help.

I also removed my MD - very easy. It also allows the gun to be dry fired safely.

After about 500 rounds through my SR9c, I only had one FTF. This happened the first time I tried shooting it with my weak hand. The brass ejected fine, but the slide didn't finishing pushing the new round in. I gripped tighter with the subsequent rounds with no issues. Pretty conclusive that it was due to limp wrist.

BrianSW99 wrote:The MDS doesn't interfere with the strikers movement through it's channel or the breach face. It works by keeping the trigger bar from contacting the sear, so when you pull the trigger it's not making contact with anything.

I don't think that's how it works on the SR9c (unless mine is defective). I can pull the trigger with the magazine removed and watch the striker indicator come back through the endcap and then jump forward as the sear is released. The only difference between with and without a magazine is that, if you drop a pencil eraser-first into the barrel against the breechface and pull the trigger, it jumps just a smidge with the magazine inserted, but not at all with the magazine removed.

There is no difference in trigger pull with or without a magazine inserted.

Since it hasn't happened in 200 rounds, I'm inclined to think it was a shooter-induced malfunction, but I'll probably pull the MDS out anyway, just to remove one more possible complication.

Here's an update to the saga. I removed the MDS when I cleaned the pistol the other day (the striker and channel were nasty looking!). The MDS fits into a notch in the slide, and it does block the striker from passing through the breech face. The only change I noticed so far (haven't had a chance to shoot it yet) is that the magazine will click home a smidge easier now, but it will not shoot out of the mag well when the release is pushed, either. The gun will now fire with the magazine removed just like it does with a magazine inserted, and I have not noticed a change in trigger pull weight.